54 Dr. Mac Culloch on Malaria on Ship-board, 



causes proved : if it is not contagion, it must be miasma, or 

 malaria. And, as I have formerly shown, this cause is widely 

 spread : while, very certainly, these low, nervous fevers will be 

 found to occur or prevail chiefly or solely where that cause 

 exists, and while also the ver)^ individual cause, the exposure, 

 can itself be often traced with care. Further, this low fever 

 will be found chiefly to prevail in the very period and season 

 of malaria ; as its range is that of summer, and chiefly of 

 autumn, extending as far with us, often, as Christmas. 



And, lastly, the disorder itself has a peculiarity of character 

 which ought always to have explained its true nature and 

 cause. It does not propagate itself, as I formerly remarked of 

 these fevers generally ; while physicians, pursuing the same 

 systematic error, have, not without plausibility, according to 

 their own views, attributed this, in all such cases, to the mild^ 

 ness or slight severity of the case or disease. Still more, the 

 mild fevers arising from contagion, or the real typhus mitior of 

 nosology, is commonly short in duration, while slender in point 

 of severity. But the very reverse is the common character of 

 the nervous fever which is most common ; or its duration is 

 commonly very great, even when it is so slight as scarcely to 

 disable the patient. And, on this, I may remark generally, 

 that if three weeks is a very general average duration for true 

 typhus, the very mild cases will not last so long ; while four, 

 or five, or six being the much more common extent of remit- 

 tent or marsh fever, so will that form the period of the very 

 mildest nervous fever that exists, as arising from malaria. And 

 whenever a very mild fever does last many weeks, there being 

 no relapse, we may be quite sure that its cause is malaria ; that 

 it is a marsh fever, not typhus mitior. Thus, also, a relapse 

 is rare in the very mild contagious fever, while it is so common 

 in the marsh fevers, of whatever degree of severity, that we 

 almost pronounce with certainty on its character, if there is 

 even one relapse ; most certainly and confidently, if there 

 should be more than one, or if the symptoms should spin out 

 to an interminable length. 



There is one other fact, very common in these mild fevers ; 

 and it is, at the same time, both so remarkable, and so charac- 

 teristic, that it is only wonderful how it should be so very gene- 



